1. Field of the Invention
This invention relates to a multi-layer composite coating composition which comprises a first coat which incorporates a catalyst which is essentially inert in such first coat and a second coat which is applied onto the first coat, or, in the alternative, onto an intermediate coat which has been applied onto the first coat, which second coat then obtains use of the catalyst from the first coat through catalyst migration or permeation into the second coat. This invention is particularly useful in automotive coating applications which incorporate a colored basecoat followed by the application of a clearcoat prior to the cure of the basecoat itself.
2. Description of the Prior Art
The use of clearcoat and basecoat compositions is known in the art. For example, U.S. Pat. Nos. 4,871,806 and 4,912,154 teach the use of clearcoat/basecoat systems. Additionally, applications of migratory catalysts where the catalyst is incorporated in the clearcoat or topcoat are known in the art. For example, Kraus, U.S. Pat. No. 4,891,248, teaches a process for promoting the cure of a two-component polyurethane coating by applying to the polyurethane while it is in a wet or semi-dry state a composition consisting essentially of a hydroxy functional polymer and a catalyst for the reaction of hydroxyl groups and isocyanate groups.
Porter, et al., U.S. Pat. No. 4,917,955 teach clearcoat/basecoat systems wherein the basecoat is free of a cure catalyst and comprises a liquid crosslinkable composition comprising a polyepoxide and a polyacid and the clearcoat comprises a catalyst in an amount sufficient to cure both the basecoat and the clearcoat.